Chevrolet 2003 Avalanche Owner's Manual page 84

Rear Door Security Locks
With this feature, you can lock the rear doors so they
can't be opened from the inside by passengers.
This feature is located on
the inside edge of the rear
doors.
To use one of the locks, do the following:
1. Open one of the rear doors.
2. Move the lever forward to engage the rear door
security iock.
3. Close the door.
4. Do the same thing to the other rear door.
The rear doors or your vehicle cannot be opened from
the inside when this feature is in use. If you want to
open the rear door while the security lock is engaged,
unlock the door and open the door from the outside.
Move the lever rearward to disengage the child security
lock feature.
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